"If we don't, who will?" said Lisa Higgins, a dog handler with the Louisiana Search and Rescue Dog Team. "Somebody has to find the missing."

University of South Florida researchers have discovered 55 graves on the grounds, five more than they previously believed existed at the shuttered north Florida reform school with a history of extreme abuse.

The number of burials is also 24 more than official records indicate, according Erin Kimmerle, a USF associate professor leading the team of researchers. They began excavating graves in September.

"We have actually located bodies that date as far as 1690," Higgins said. "We've found POW's from the Civil War."

Much of the area crews searched Tuesday was heavily wooded, making it difficult for Higgins and her dog, Dixie, to cover ground quickly.

The school covers hundreds of acres. Because of the property's size, USF researchers said Dixie and her counterparts are the key to uncovering unmarked graves.

Dog handlers from Broward County, Connecticut and Louisiana are working with a group called NecroSearch as volunteers.

"The dogs indicate the presence of those remains in different ways," Higgins said. "Some will bark. Some will down."

Dixie is trained to sit, and she did.

"Oh, good girl. Good job," Higgins told her dog after she detected the odor of human decomposition. "Let's keep searching. She is totally sure of this one."

If secrets are hidden here, they likely won't be for much longer.

"We're being asked essentially to do everything we can so that when we're done here everyone feels confident that we didn't leave anyone behind," Kimmerle said.

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